The Astronomy Nexushttp://www.astronexus.com
The Astronomy Nexus is a personal website covering all sorts of topics on astronomy and other interests.enUpdate to HYG catalog and new deep-sky objects (DSO) catalog.http://www.astronexus.com/node/185
<div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"></div></div></div>Mon, 24 Nov 2014 02:56:03 +0000David185 at http://www.astronexus.comhttp://www.astronexus.com/node/185#commentsEndeavour updates: Getting aroundhttp://www.astronexus.com/node/178
<div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p>There is now a navigation tool for <a href="/endeavour/chart">star charts</a>. It's in the upper left part of the chart display. With it, you can retarget the current chart, choose different zoom levels for many charts, and return to a "Home" view if you've been viewing from remote locations.</p>
<p><img src="/app/core/img/nav.png" alt="Navigation tools" /></p>
<p>Additional details after the break:</p>
<ul><li><b>Zoom In / Zoom Out (Atlas charts only): </b> Increase or decrease the magnification of the chart by one step. Each step increases or decreases the chart area by a factor of 2.</li>
<li><b>Arrows:</b> Retarget the chart on a point that is in the specified direction. The step size is about 1/2 the width or height of the chart.</li>
<li><b>Home:</b> Set the Location of the chart to the Sun, and the Target to a default value. </li>
</ul><p>The Zoom In and Zoom Out options are only available when the chart type is "Atlas", since this type has 16 distinct zoom levels. The other chart types (such as Naked Eye or Classic Atlases) turn these options off. For this reason, the "default" chart type has changed from Naked Eye to Atlas.</p>
</div></div></div>Sun, 27 Jul 2014 17:44:55 +0000David178 at http://www.astronexus.comhttp://www.astronexus.com/node/178#commentsEndeavour updateshttp://www.astronexus.com/node/177
<div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p>A few changes to the interface:</p>
<ul><li>Star HUD is now triggered by click, rather than mouseover/mouseout, so it's "sticky". Since it's less HUD-like, the option has been renamed to "star details". The star's details will remain on screen till you click the star again (or click a different star to get its details)</li>
<li>For most stars and deep-sky objects, the object's name in the details (in bold text) is a link. Click it to recenter the chart on that object.</li>
<li>For stars with known distances, there is a "Travel" area in the star's details. Click "Go to [star ID]" to set the chart location to that star. From remote locations, the "Travel" area will also have a "Back to Sun" option to quickly return to the Sun.</li>
<li>The Location and Target star lists are now in the Advanced Chart Settings.</li>
</ul></div></div></div>Sun, 29 Jun 2014 19:48:53 +0000David177 at http://www.astronexus.comhttp://www.astronexus.com/node/177#commentsCh...ch...ch...changeshttp://www.astronexus.com/node/176
<div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p>A few changes to <a href="/endeavour">Endeavour</a> recently:</p>
<p>First, I've rearranged the "Chart Labels" into a more compact arrangement. Related options (like those for chart-level settings, or star labels, or deep-sky object labels) are in the same columns. This should make it a little easier to keep track of option settings with similar functions.</p>
<p>Second, there's now a "Variables" label option. Enable it, and any Hipparcos variables with a major variable star designation (approximately 6,000 stars in the database) will be highlighted with a circle around the star symbol, just as in most star atlases. Their star label will also appear, regardless of any other settings. "Variables" mode is enabled by default in all Atlas Levels of 7 and up, as well as the "deeper" classic star atlas modes such as <em>Uranometria</em> and <em>Millennium Star Atlas</em>.</p>
<p>(On a somewhat technical note: "major variable star designation" basically means a traditional Bayer or Flamsteed ID (such as δ Cep), a classic one- or two-letter ID (such as R CrB or RR Lyr) or a "V" ID (such as V450 Aql). Stars with only a "NSV" (New Catalogue of Suspected Variable Stars) designation have not been included.)</p>
<p>Third, when your chart location is the Sun or very close to it, the HUD for a variable star will contain an estimate of the star's magnitude range. This estimate is based on the 5% and 95% percentile brightnesses measured by Hipparcos, which performed its observations over a 4 year time frame. As a result, many long-period or irregular variables were not sampled over their entire range, and some very wide-ranging variables could not be measured accurately at their minimum. Thus the variable range shown in <em>Endeavour</em> is smaller than the actual range for some stars, which will actually have somewhat brighter maxima or fainter minima than what Hipparcos was able to observe.</p>
</div></div></div>Sat, 17 May 2014 22:39:37 +0000David176 at http://www.astronexus.comhttp://www.astronexus.com/node/176#commentsGet a move onhttp://www.astronexus.com/node/175
<div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p><a href="/endeavour">Endeavour</a> now has stellar motion markers, allowing you to see where the stars were far in the past, or will be far in the future. Here's an example, showing where the stars will be 10,000 years in the future:</p>
<p><img src="/app/endv/img/pm-markers.png" /></p>
<p>Stellar motion markers are set in the "Advanced Chart Settings", using a non-zero number for "Stellar motion markers". Positive numbers represent times in the future, negative ones in the past, in years before or after the chart epoch (2000.0). If you have changed the year number, click "Update Chart" to load updated stellar data. Finally, under Chart Labels, check the "Stellar motions" box on or off to show or hide the markers, just like any other label option.</p>
<p>Stellar motions require additional network traffic and chart calculations, so are not enabled by default on all display modes. They are shown by default in <em>Millennium Star Atlas</em> mode, where the markers represent 1,000 years of future motion, just like the print atlas. The following atlas modes also calculate markers, but hide them by default (check "Stellar motions" in Chart Labels to display them):</p>
<ul><li><em>Uranometria</em> (both versions): 2500 yrs future</li>
<li>Atlas zoom levels 7 - 9: 2000 yrs future</li>
<li>Atlas zoom levels 10 - 12: 1000 yrs future</li>
</ul><p>Stellar motion markers are not available in "Telescope" modes, since the UCAC-4 data subset in <em>Endeavour</em> does not currently contain stellar motion data. They are available for all other atlas modes, which use Hipparcos and Tycho-2 stars. For any such atlas mode, to enable stellar motion markers, edit the "Advanced Chart Settings" as described above.</p>
</div></div></div>Mon, 12 May 2014 05:47:30 +0000David175 at http://www.astronexus.comhttp://www.astronexus.com/node/175#commentsEndeavour: additional large star cataloghttp://www.astronexus.com/node/174
<div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p>The <a href="/endeavour/">Endeavour</a> application now has a large subset of the <a href="http://arxiv.org/abs/1212.6182">fourth US Naval Observatory CCD Astrograph Catalog (UCAC4)</a>. The subset contains over 30 million stars to magnitude +15.0.</p>
<p>Here's an example of the difference. This is the M13 area using the Tycho-2 catalog:</p>
<p><img src="/app/endv/img/m13-tyc.png" /></p>
<p>And this is the M13 area with the UCAC-4 subset:</p>
<p><img src="/app/endv/img/m13-ucac.png" /></p>
<p>There are now three additional chart presets: Telescope (small), Telescope (medium), and Telescope (large). These use the UCAC-4 data along with deep-sky objects to show a representation of the sky as seen, under dark skies, in three size ranges of telescope (approximately 4", 8", and 16" apertures respectively).</p>
<p>UCAC-4 stars are displayed when all of these criteria are met:</p>
<ol><li>The "Enable large star catalogs" option is enabled.</li>
<li>The chart scale is greater than 20.</li>
<li>The chart star magnitude limit is greater than +12.0.</li>
<li>Your source location (where you're viewing from) is the Sun (Sol).</li>
</ol><p>If large star catalogs are enabled, but the scale is too low or the magnitude limit is too bright, you'll get the Tycho-2 catalog instead. Also, as with the Tycho-2 catalog, the UCAC-4 catalog does not contain distance information, so it's not available when your "source location" is remote (away from the Sun). For star atlas views near the Sun, though, enjoy over 30 million new stars!</p>
</div></div></div>Mon, 10 Mar 2014 01:21:54 +0000David174 at http://www.astronexus.comhttp://www.astronexus.com/node/174#commentsEndeavourhttp://www.astronexus.com/node/173
<div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p>I've just completed a monster rewrite of the old Distant Worlds star charting application. It now has a bunch of new features:</p>
<ul><li>Modern HTML5 application. In particular, many label settings (e.g., coordinate grids, star labels, constellation names) no longer require a page reload for every chart. Change one of these settings and the chart changes immediately.</li>
<li>Many more preset chart levels including "classic" star atlases like <em>Uranometria</em> and<br />
the Millennium Star Atlas</li>
<li>Over 200,000 deep sky objects including galaxies down to magnitude +17</li>
<li>Deep-sky objects optionally link to Digitized Sky Survey images</li>
<li>Deep-sky objects, like stars, can be searched for by name and used as target locations.</li>
<li>A database that can eventually contain larger catalogs than the HYG and Tycho-2 catalogs currently in use.</li>
<li>And...you can still visit every one of the over 100,000 stars in the HYG catalog and see what the universe looks like from them.</li>
</ul><p>Because of all this, the <a href="/endeavour/chart">new application</a> got a rename: it's now <i>Endeavour</i>, after one of the most famous ships from which people pursued astronomical observations. In <i>Endeavour's</i> case, it was a rare transit of Venus, at a time when a transit was one of the few ways to measure the Solar System. </p>
<p>As an HTML5 application, <i>Endeavour</i> may not work on very old Web browsers (specifically, versions of Internet Explorer older than version 9). For people with these old Web browsers, or those who simply prefer the older version for some reason, the older application is still <a href="/endeavour/old">available here</a> indefinitely.</p>
</div></div></div>Sun, 09 Mar 2014 03:53:31 +0000David173 at http://www.astronexus.comhttp://www.astronexus.com/node/173#commentsLong time cominghttp://www.astronexus.com/node/170
<div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p>Yes, I know this site has been pretty dead lately. Interstate moves can do that. Fortunately, that's been over for a while, giving me some time to make updates.</p>
<p>The Star Mapper has gotten a big -- and long overdue -- update. New features include:</p>
<ul><li>When you hover over a star to get its information, the information appears next to the star instead of in the upper right. The star itself gets highlighted as well.</li>
<li>The old, somewhat awkward selection menus are gone. Instead, you can enter locations directly. You can enter all common star designations (proper names, Bayer Greek letters, and IDs in star catalogs like Hipparcos and Gliese), as well as stellar coordinates in equatorial form (i.e., right ascension and declination). So you can cut and paste most names or coordinates from a Web site and have the map recognize them as a valid source or target. </li>
<li>The list of commonly used stars is still there. It just selects a star name for you automatically.</li>
<li>A blank selection for a star defaults to the Sun. So to view conventional Earth-based star charts, you can leave the source blank. To see the Sun, specifically, from other stars, you can leave the target blank.</li>
<li>The color scheme got a few tweaks, mostly to make nearby and Sunlike stars a bit more apparent.</li>
<li>The database queries are now more efficient, which not only makes the map faster, but also makes it possible to show more stars on the same map. There is no longer a hard magnitude limit with chart scale, the way there used to be.</li>
<li>A number of fainter stars were missing their Bayer and Flamsteed designations, because they didn't appear in the <em>Yale Bright Star Catalog</em>, my main source for this information. I have added approximately 220 Bayer and Flamsteed designations from <em>Flamsteed's Missing Stars, Wagman, M., Journ. History of Astronomy, Vol. 18, No. 3. p.209 (1987)</em>.</li>
<li>Miscellaneous scrungy code got cleaned up a bit.</li>
<ul></ul></ul></div></div></div>Sat, 07 Sep 2013 19:22:37 +0000David170 at http://www.astronexus.comhttp://www.astronexus.com/node/170#commentsGitHubhttp://www.astronexus.com/node/169
<div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p>I am hosting some of the larger downloads on this site on <a href="https://github.com/astronexus">GitHub</a> now. The most current version of the HYG database will always be posted there. Any publicly available code relevant to the site will go there as well.</p>
</div></div></div>Mon, 19 Sep 2011 22:45:31 +0000David169 at http://www.astronexus.comhttp://www.astronexus.com/node/169#commentsLunar eclipse shotshttp://www.astronexus.com/node/168
<div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p>It was clear for just long enough here in Colorado to get a good view of the eclipse. I got a number of decent shots with just a compact camera (Panasonic Lumix FZ-28, most at the max zoom level of 18x). As I've told a friend once, since the albedo of the Moon is similar to that of fresh asphalt, getting the right exposure settings for the full Moon is about as hard as getting them for a sunlit street. With an eclipse going on, it's a little tougher, but aggressive exposure bracketing solves many ills, and is very simple with almost any digital camera.</p>
<p>Here's one of my favorite shots (click to embiggen):</p>
<p><a href="/images/astro/astrophoto/2010eclipse/P1020558.JPG"><img src="/images/astro/astrophoto/2010eclipse/P1020558-a.jpg" /></a></p>
<p>More images below the break:</p>
<!--break--><p>Halfway through the partial phase. There were still some clouds, so the Moon has a halo (and it was hard to get good focus):</p>
<p><a href="/images/astro/astrophoto/2010eclipse/P1020464.JPG"><img src="/images/astro/astrophoto/2010eclipse/P1020464-a.jpg" /></a></p>
<p>The beginning of totality:</p>
<p><a href="/images/astro/astrophoto/2010eclipse/P1020515.JPG"><img src="/images/astro/astrophoto/2010eclipse/P1020515-a.jpg" /></a></p>
<p>A wider-field shot showing some of the stars of Gemini and Taurus. The Moon was very close to the open cluster M35, which was too faint to show with the exposure I used: </p>
<p><a href="/images/astro/astrophoto/2010eclipse/P1020566.JPG"><img src="/images/astro/astrophoto/2010eclipse/P1020566-a.jpg" /></a></p>
<p>Mid-totality. Unfortunately, the clouds came back right afterward:</p>
<p><a href="/images/astro/astrophoto/2010eclipse/P1020589.JPG"><img src="/images/astro/astrophoto/2010eclipse/P1020589-a.jpg" /></a></p>
</div></div></div>Tue, 21 Dec 2010 17:13:32 +0000David168 at http://www.astronexus.comhttp://www.astronexus.com/node/168#comments